Adsorptive processes are an established means of separation used to separate gas phase components in multicomponent gas streams found in many industrial applications. Many industrial gas streams contain contaminant components which may be advantageously separated from the gas stream prior to some downstream use. Adsorptive separation processes have been adapted for use in many such industrial applications.
Thermal and pressure swing adsorption processes (TSA and PSA) as known in the prior art have both been successfully adapted to remove contaminant components from commercially important gas streams, making use of specialized adsorbent materials to adsorb contaminants from the input, or feed gas stream, leaving the desired product gas stream substantially free of the contaminants. Such adsorbent materials may then be cyclically regenerated to subsequently desorb the contaminant component which may be exhausted or otherwise disposed, prior to re-use of the adsorbent material.
In conventional adsorptive separation systems, the regeneration of the adsorbent material(s) requires the application of a purge stream that is substantially free of the contaminant component in contact with the adsorbent, in order to effectively desorb the contaminant component from the adsorbent material. In the case of TSA, the purge stream is heated to a temperature sufficient to desorb the contaminant from the adsorbent. In the case of PSA, purified product gas is typically used to purge the contaminant from the adsorbent. Such purge gas must typically be selected from gases external to the available feed gas stream, such as in the case of a TSA system, an exemplary heated inert (substantially free of contaminant component(s) and other gas components which may inhibit desorption and purge of the adsorbed contaminant from the adsorbent material) purge gas, or purified product gas in the case of a PSA system. The use of such contaminant free purge gas streams typically influence the efficiency of the adsorptive process, by reducing product recovery in the case of PSA, and/or increasing the cost such as in the provision of a suitable heated contaminant-free purge gas stream in the case of TSA. In all cases, the overall achievable efficiency of the adsorptive separation system is limited by the quantity and cost (in terms of external gas and heat energy or lost product gas) of purge gas required to desorb the contaminant from the adsorbent material during regeneration.